Upgrade google-generativeai SDK to latest version

- Updated from 0.3.2 to >=0.8.0
- Fixes compatibility with current Gemini models
- Should resolve model not found errors

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

requirements.txt

@@ -5,6 +5,6 @@ python-dotenv==1.0.0
 httpx==0.26.0
 sqlalchemy==2.0.25
 aiosqlite==0.19.0
-google-generativeai==0.3.2
+google-generativeai>=0.8.0
 pydantic==2.5.3
 pydantic-settings==2.1.0